https://gitlab.synchro.net/main/sbbs/-/issues/592#note_3948

I'm currently working on a javascript version of the default user settings, which will allow the sysop to customize it fairly easily.To achieve what you're wanting, you could just pick a flag to use to restrict user's ability to forward messages to them to their email account and a line or two of code. I'm waiting for DM to come back with suggestions for improvement, and I'll add an example into the script.
--- SBBSecho 3.20-Linux
* Origin: Vertrauen - [vert/cvs/bbs].synchro.net (1:103/705)